Advanced Oxidation Process: Applications and Prospects

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Catalysts catalysts	3.8	6.8	2011	12.9 Days	CHF 2200
International Journal of Environmental Research and Public Health ijerph	-	7.3	2004	24.3 Days	CHF 2500
Processes processes	2.8	5.1	2013	14.4 Days	CHF 2400
Sci sci	-	4.5	2019	27.4 Days	CHF 1200
Water water	3.0	5.8	2009	16.5 Days	CHF 2600

4 pages, 225 KiB

Open AccessEditorial

Advanced Oxidation Process: Applications and Prospects

by Gassan Hodaifa, Antonio Zuorro, Joaquín R. Dominguez, Juan García Rodríguez, José A. Peres, Zacharias Frontistis and Mha Albqmi

Water 2023, 15(19), 3444; https://doi.org/10.3390/w15193444 - 30 Sep 2023

Cited by 2 | Viewed by 1954

Abstract

The generation of waste has increased significantly over the last 50 years [...] Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

15 pages, 2878 KiB

Open AccessArticle

Enhanced Removal of Doxycycline by Simultaneous Potassium Ferrate(VI) and Montmorillonite: Reaction Mechanism and Synergistic Effect

by Hangli Zhang, Shujuan Wang, Ji Shu and Hongyu Wang

Water 2023, 15(9), 1758; https://doi.org/10.3390/w15091758 - 3 May 2023

Cited by 1 | Viewed by 1855

Abstract

Doxycycline (DOX), a typical antibiotic, is harmful to aquatic ecosystems and human health. This study presents DOX removal by potassium ferrate (Fe(VI)) and montmorillonite and investigates the effect of Fe(VI) dosage, reaction time, initial pH value, montmorillonite dosage, adsorption pH, time and temperature [...] Read more.

Doxycycline (DOX), a typical antibiotic, is harmful to aquatic ecosystems and human health. This study presents DOX removal by potassium ferrate (Fe(VI)) and montmorillonite and investigates the effect of Fe(VI) dosage, reaction time, initial pH value, montmorillonite dosage, adsorption pH, time and temperature on DOX removal. The results show that DOX removal increases when increasing the Fe(VI) dosage, with the optimal condition for DOX removal (~97%) by Fe(VI) observed under a molar ratio ([Fe(VI)]:[DOX]) of 30:1 at pH 7. The reaction of DOX with Fe(VI) obeyed second-order kinetics with a rate constant of 10.7 ± 0.45 M⁻¹ s⁻¹ at pH 7. The limited promotion (~4%) of DOX adsorption by montmorillonite was observed when the temperature increased and the pH decreased. Moreover, the synergetic effect of Fe(VI) and montmorillonite on DOX removal was obtained when comparing the various types of dosing sequences (Fe(VI) oxidation first and then adsorption; adsorption first and then Fe(VI) oxidation; simultaneous oxidation and adsorption). The best synergistic effect of DOX removal (97%) was observed under the simultaneous addition of Fe(VI) and montmorillonite, maintaining the Fe(VI) dosage (from 30:1 to 5:1). Five intermediates were detected during DOX degradation, and a plausible DOX degradation pathway was proposed. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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12 pages, 2615 KiB

Open AccessArticle

Efficient Removal of Rhodamine B in Wastewater via Activation of Persulfate by MnO₂ with Different Morphologies

by Xinyi Zhang, Xinrui Gan, Shihu Cao, Jiangwei Shang and Xiuwen Cheng

Water 2023, 15(4), 735; https://doi.org/10.3390/w15040735 - 13 Feb 2023

Cited by 4 | Viewed by 2821

Abstract

In recent years, typical organic pollutants were frequently found in aquatic environments. Among them, synthetic dyes were widely used in many industries, which resulting in a large amount of wastewater contained dyes. Because of the characteristic of complex components, poor biodegradability and high [...] Read more.

In recent years, typical organic pollutants were frequently found in aquatic environments. Among them, synthetic dyes were widely used in many industries, which resulting in a large amount of wastewater contained dyes. Because of the characteristic of complex components, poor biodegradability and high toxicity, this kind of wastewater brought lots of harm to the ecological environment and organism. In this study, three different types of manganese dioxide (MnO₂) with the rod-like, needle-like and mixed morphologies respectively were successfully fabricated by hydrothermal method with changing the preparation conditions and addition of the metal ions, and utilized as activator of persulfate (PS) to remove the dyes aqueous. Subsequently, these MnO₂ nanocomposite was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements. In addition, Rhodamine B (Rh B), as a representative substance of xanthene dyes was chosen as the target degradants to researched and compared the efficiency of removal via PS activated by different MnO₂. By exploring the influences of different reaction parameters on the result of removal, results indicated that PS activated by the acicular MnO₂ (α-MnO₂) can remove 97.41% of Rh B over 60 min, with the optimal catalyst/PS ratio of 2:1 (the concentration of the α-MnO₂ and PS were 1.2 g/L and 0.6 g/L, respectively), pH value of 3, at the temperature of 20 °C. Meanwhile, the probable degradation mechanism was also proposed. At last, as the catalyst was reused for four times, the degradation rate of target degradants decreased less than 10%. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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21 pages, 1297 KiB

Open AccessEditor’s ChoiceReview

Fenton Reaction–Unique but Still Mysterious

by Frantisek Kastanek, Marketa Spacilova, Pavel Krystynik, Martina Dlaskova and Olga Solcova

Processes 2023, 11(2), 432; https://doi.org/10.3390/pr11020432 - 1 Feb 2023

Cited by 17 | Viewed by 6431

Abstract

This study is devoted to the Fenton reaction, which, despite hundreds of reports in a number of scientific journals, provides opportunities for further investigation of its use as a method of advanced oxidation of organic macro- and micropollutants in its diverse variations and [...] Read more.

This study is devoted to the Fenton reaction, which, despite hundreds of reports in a number of scientific journals, provides opportunities for further investigation of its use as a method of advanced oxidation of organic macro- and micropollutants in its diverse variations and hybrid systems. It transpires that, for example, the choice of the concentrations and ratios of basic chemical substances, i.e., hydrogen peroxide and catalysts based on the Fe²⁺ ion or other transition metals in homogeneous and heterogeneous arrangements for reactions with various pollutants, is for now the result of the experimental determination of rather randomly selected quantities, requiring further optimizations. The research to date also shows the indispensability of the Fenton reaction related to environmental issues, as it represents the pillar of all advanced oxidation processes, regarding the idea of oxidative hydroxide radicals. This study tries to summarize not only the current knowledge of the Fenton process and identify its advantages, but also the problems that need to be solved. Based on these findings, we identified the necessary steps affecting its further development that need to be resolved and should be the focus of further research related to the Fenton process. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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22 pages, 5032 KiB

Open AccessArticle

Treatment of Winery Wastewater by Combined Almond Skin Coagulant and Sulfate Radicals: Assessment of

{HSO}_{5}^{-}

Activators

by Nuno Jorge, Ana R. Teixeira, Lisete Fernandes, Sílvia Afonso, Ivo Oliveira, Berta Gonçalves, Marco S. Lucas and José A. Peres

Int. J. Environ. Res. Public Health 2023, 20(3), 2486; https://doi.org/10.3390/ijerph20032486 - 30 Jan 2023

Cited by 6 | Viewed by 1994

Abstract

The large production of wine and almonds leads to the generation of sub-products, such as winery wastewater (WW) and almond skin. WW is characterized by its high content of recalcitrant organic matter (biodegradability index < 0.30). Therefore, the aim of this work was [...] Read more.

The large production of wine and almonds leads to the generation of sub-products, such as winery wastewater (WW) and almond skin. WW is characterized by its high content of recalcitrant organic matter (biodegradability index < 0.30). Therefore, the aim of this work was to (1) apply the coagulation–flocculation–decantation (CFD) process with an organic coagulant based on almond skin extract (ASE), (2) treat the organic recalcitrant matter through sulfate radical advanced oxidation processes (SR-AOPs) and (3) evaluate the efficiency of combined CFD with UV-A, UV-C and ultrasound (US) reactors. The CFD process was applied with variation in the ASE concentration vs. pH, with results showing a chemical oxygen demand (COD) removal of 61.2% (0.5 g/L ASE, pH = 3.0). After CFD, the germination index (GI) of cucumber and corn seeds was ≥80%; thus, the sludge can be recycled as fertilizer. The SR-AOP initial conditions were achieved by the application of a Box–Behnken response surface methodology, which described the relationship between three independent variables (peroxymonosulfate (PMS) concentration, cobalt (Co²⁺) concentration and UV-A radiation intensity). Afterwards, the SR-AOPs were optimized by varying the pH, temperature, catalyst type and reagent addition manner. With the application of CFD as a pre-treatment followed by SR-AOP under optimal conditions (pH = 6.0, [PMS] = 5.88 mM, [Co²⁺] = 5 mM, T = 343 K, reaction time 240 min), the COD removal increased to 85.9, 82.6 and 80.2%, respectively, for UV-A, UV-C and US reactors. All treated wastewater met the Portuguese legislation for discharge in a municipal sewage network (COD ≤ 1000 mg O₂/L). As a final remark, the combination of CFD with SR-AOPs is a sustainable, safe and clean strategy for WW treatment and subproduct valorization. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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29 pages, 3630 KiB

Open AccessFeature PaperReview

Investigation of Advanced Oxidation Process in the Presence of TiO₂ Semiconductor as Photocatalyst: Property, Principle, Kinetic Analysis, and Photocatalytic Activity

by Amir Hossein Navidpour, Sedigheh Abbasi, Donghao Li, Amin Mojiri and John L. Zhou

Catalysts 2023, 13(2), 232; https://doi.org/10.3390/catal13020232 - 19 Jan 2023

Cited by 55 | Viewed by 7361

Abstract

Water pollution is considered a serious threat to human life. An advanced oxidation process in the presence of semiconductor photocatalysts is a popular method for the effective decomposition of organic pollutants from wastewater. TiO₂ nanoparticles are widely used as photocatalysts due to [...] Read more.

Water pollution is considered a serious threat to human life. An advanced oxidation process in the presence of semiconductor photocatalysts is a popular method for the effective decomposition of organic pollutants from wastewater. TiO₂ nanoparticles are widely used as photocatalysts due to their low cost, chemical stability, environmental compatibility and significant efficiency. The aim of this study is to review the photocatalytic processes and their mechanism, reaction kinetics, optical and electrical properties of semiconductors and unique characteristics of titanium as the most widely used photocatalyst; and to compare the photocatalytic activity between different titania phases (anatase, rutile, and brookite) and between colorful and white TiO₂ nanoparticles. Photocatalytic processes are based on the creation of electron–hole pairs. Therefore, increasing stability and separation of charge carriers could improve the photocatalytic activity. The synthesis method has a significant effect on the intensity of photocatalytic activity. The increase in the density of surface hydroxyls as well as the significant mobility of the electron–hole pairs in the anatase phase increases its photocatalytic activity compared to other phases. Electronic and structural changes lead to the synthesis of colored titania with different photocatalytic properties. Among colored titania materials, black TiO₂ showed promising photocatalytic activity due to the formation of surface defects including oxygen vacancies, increasing the interaction with the light irradiation and the lifetime of photogenerated electron–hole pairs. Among non-metal elements, nitrogen doping could be effectively used to drive visible light-activated TiO₂. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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15 pages, 4121 KiB

Open AccessArticle

Degradation of Agro-Industrial Wastewater Model Compound by UV-A-Fenton Process: Batch vs. Continuous Mode

by Nuno Jorge, Ana R. Teixeira, José R. Fernandes, Ivo Oliveira, Marco S. Lucas and José A. Peres

Int. J. Environ. Res. Public Health 2023, 20(2), 1276; https://doi.org/10.3390/ijerph20021276 - 10 Jan 2023

Cited by 9 | Viewed by 1591

Abstract

The degradation of a model agro-industrial wastewater phenolic compound (caffeic acid, CA) by a UV-A-Fenton system was investigated in this work. Experiments were carried out in order to compare batch and continuous mode. Initially, batch experiments showed that UV-A-Fenton at pH 3.0 (pH [...] Read more.

The degradation of a model agro-industrial wastewater phenolic compound (caffeic acid, CA) by a UV-A-Fenton system was investigated in this work. Experiments were carried out in order to compare batch and continuous mode. Initially, batch experiments showed that UV-A-Fenton at pH 3.0 (pH of CA solution) achieved a higher generation of

{HO}^{•}

, leading to high CA degradation (>99.5%). The influence of different operational conditions, such as H₂O₂ and Fe²⁺ concentrations, were evaluated. The results fit a pseudo first-order (PFO) kinetic model, and a high kinetic rate of CA removal was observed, with a [CA] = 5.5 × 10⁻⁴ mol/L, [H₂O₂] = 2.2 × 10⁻³ mol/L and [Fe²⁺] = 1.1 × 10⁻⁴ mol/L (k_CA = 0.694 min⁻¹), with an electric energy per order (

E_{EO}

) of 7.23 kWh m⁻³ order⁻¹. Under the same operational conditions, experiments in continuous mode were performed under different flow rates. The results showed that CA achieved a steady state with higher space-times (θ = 0.04) in comparison to dissolved organic carbon (DOC) removal (θ = 0–0.020). The results showed that by increasing the flow rate (F) from 1 to 4 mL min⁻¹, the CA and DOC removal rate increased significantly (k_CA = 0.468 min⁻¹; k_DOC = 0.00896 min⁻¹). It is concluded that continuous modes are advantageous systems that can be adapted to wastewater treatment plants for the treatment of real agro-industrial wastewaters. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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15 pages, 4557 KiB

Open AccessArticle

Oxidation Catalysis of Au Nano-Particles Immobilized on Titanium(IV)- and Alkylthiol-Functionalized SBA-15 Type Mesoporous Silicate Supports

by Tomoki Haketa, Toshiaki Nozawa, Jun Nakazawa, Masaya Okamura and Shiro Hikichi

Catalysts 2023, 13(1), 35; https://doi.org/10.3390/catal13010035 - 24 Dec 2022

Cited by 1 | Viewed by 1606

Abstract

Novel Au nano-particle catalysts immobilized on both titanium(IV)- and alkylthiol-functionalized SBA-15 type ordered mesoporous silicate supports were developed. The bi-functionalized SBA-15 type support could be synthesized by a one-pot method. To the synthesized supports, Au was immobilized by the reaction of the alkylthiol [...] Read more.

Novel Au nano-particle catalysts immobilized on both titanium(IV)- and alkylthiol-functionalized SBA-15 type ordered mesoporous silicate supports were developed. The bi-functionalized SBA-15 type support could be synthesized by a one-pot method. To the synthesized supports, Au was immobilized by the reaction of the alkylthiol groups on the supports with AuCl₄⁻, following reduction with NaBH₄. The immobilized amount and the formed structures and the electronic property of the Au species depended on the loading of alkylthiol. The moderate size (2–3 nm) nano particulate Au sites formed on Ti(0.5)-SBA^SH(0.5) were negatively charged. The aerobic alcohol oxidation activity of the catalysts depended on the loading of alkylthiol and the structure of the Au nano-particles. The non-thiol-functionalized catalyst (Au/Ti(0.5)-SBA^SH(0)) composed of the large (5–30 nm) and the higher thiol-loaded catalyst (Au/Ti(0.5)-SBA^SH(8)) composed of the small cationic Au species were almost inactive. The most active catalyst was Au/Ti(0.5)-SBA^SH(0.5) composed of the electron-rich Au nano-particles formed by the electron donation from the highly dispersed thiol groups. Styrene oxidation activity in the presence of 1-phenylethanol with O₂ depended on the loadings of titanium(IV) on the Au/Ti(x)-SBA^SH(0.5). The titanium(IV) sites trapped the H₂O₂ generated through the alcohol oxidation reaction, and also contributed to the alkene oxidation by activating the trapped H₂O₂. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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17 pages, 3634 KiB

Open AccessArticle

Checking the Efficiency of a Magnetic Graphene Oxide–Titania Material for Catalytic and Photocatalytic Ozonation Reactions in Water

by Manuel Checa, Vicente Montes, Javier Rivas and Fernando J. Beltrán

Catalysts 2022, 12(12), 1587; https://doi.org/10.3390/catal12121587 - 6 Dec 2022

Cited by 5 | Viewed by 2352

Abstract

An easily recoverable photo-catalyst in solid form has been synthesized and applied in catalytic ozonation in the presence of primidone. Maghemite, graphene oxide and titania (FeGOTi) constituted the solid. Additionally, titania (TiO₂) and graphene oxide–titania (GOTi) catalysts were also tested for [...] Read more.

An easily recoverable photo-catalyst in solid form has been synthesized and applied in catalytic ozonation in the presence of primidone. Maghemite, graphene oxide and titania (FeGOTi) constituted the solid. Additionally, titania (TiO₂) and graphene oxide–titania (GOTi) catalysts were also tested for comparative reasons. The main characteristics of FeGOTi were 144 m²/g of surface area; a 1.29 Raman D and G band intensity ratio; a 26-emu g⁻¹ magnetic moment; maghemite, anatase and brookite main crystalline forms; and a 1.83 eV band gap so the catalyst can absorb up to the visible red region (677 nm). Single ozonation, photolysis, photolytic ozonation (PhOz), catalytic ozonation (CatOz) and photocatalytic ozonation (PhCatOz) were applied to remove primidone. In the presence of ozone, the complete removal of primidone was experienced in less than 15 min. In terms of mineralization, the best catalyst was GOTi in the PhCatOz processes (100% mineralization in 2 h). Meanwhile, the FeGOTi catalyst was the most efficient in CatOz. FeGOTi led, in all cases, to the highest formation of HO radicals and the lowest ozone demand. The reuse of the FeGOTi catalyst led to some loss of mineralization efficacy after four runs, likely due to C deposition, the small lixiviation of graphene oxide and Fe oxidation. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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13 pages, 2329 KiB

Open AccessArticle

Rapid AOP Method for Estrogens Removal via Persulfate Activated by Hydrodynamic Cavitation

by Petra Přibilová, Klára Odehnalová, Pavel Rudolf, František Pochylý, Štěpán Zezulka, Eliška Maršálková, Radka Opatřilová and Blahoslav Maršálek

Water 2022, 14(23), 3816; https://doi.org/10.3390/w14233816 - 23 Nov 2022

Cited by 4 | Viewed by 2043

Abstract

The production and use of manufactured chemicals have risen significantly in the last few decades. With interest in preserving and improving the state of the environment, there is also growing interested in new technologies for water purification and wastewater treatment. One frequently discussed [...] Read more.

The production and use of manufactured chemicals have risen significantly in the last few decades. With interest in preserving and improving the state of the environment, there is also growing interested in new technologies for water purification and wastewater treatment. One frequently discussed technological group is advanced oxidation processes (AOPs). AOPs using sulphur-based radicals appear to reduce the volume of organic contaminants in wastewater significantly. The use of persulfate has excellent potential to successfully eliminate the number of emerging contaminants released into the environment. The main disadvantage of sulphur-based AOPs is the need for activation. We investigated an economically and environmentally friendly solution based on hydrodynamic cavitation, which does not require heating or additional activation of chemical substances. The method was evaluated for emerging contaminant removal research, specifically for the group of steroid estrogens. The mixture of estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2) was effectively eliminated and completely removed during a treatment that lasted just a few seconds. This novel method can be used in a broad spectrum of water treatment processes or as the intensification of reactions in chemical engineering technologies. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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16 pages, 3479 KiB

Open AccessArticle

COD Reduction of Aeration Effluent by Utilizing Optimum Quantities of UV/H₂O₂/O₃ in a Small-Scale Reactor

by Mehdi Rafiee, Morteza Sabeti, Farshid Torabi and Aria Rahimbakhsh

Processes 2022, 10(11), 2441; https://doi.org/10.3390/pr10112441 - 18 Nov 2022

Cited by 6 | Viewed by 3042

Abstract

Extensive research has been carried out to figure out safe means of disposing various industrial effluents. Industrial wastewaters from the aeration industry such as heavy metals and oily substances contain a high degree of contamination. The advanced oxidation process is one of the [...] Read more.

Extensive research has been carried out to figure out safe means of disposing various industrial effluents. Industrial wastewaters from the aeration industry such as heavy metals and oily substances contain a high degree of contamination. The advanced oxidation process is one of the most effective and rapid methods of removing contaminations, which can lead to a high chemical oxygen demand (COD). The aim of the present study is to reduce the COD of an aeration effluent with the initial COD of 13,004 mg/L. About 20 sets of experimental tests were conducted to identify the contribution of H₂O₂, O₃, and UV to the treatment process. The influence of the quantities of additives and the dose of the UV irradiance were, too, among the subjects of the study. These factors were altered throughout the experiments and their mutual effects were measured. To design the experiments, Minitab software 16 was utilized. The experimental conditions were set at the standard values of 25 °C and 1 bar to minimize any uncertainty. Based on the results, a correlation was derived, which was capable of expressing the effects of the input parameters (AOPs parameters) on the response (the COD level). Finally, the optimization process was conducted to find the quantities of H₂O₂, O₃, and UV irradiance required to decrease the CODs of the effluent to their lowest possible. Based on the findings, when the doses of H₂O₂, O₃, and UV to the treatment process were 40 mg/L, 8 mg/L and 86 mWs/cm², respectively, the COD percent change was 51.5%. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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10 pages, 2188 KiB

Open AccessArticle

Effects of Low-Level Organic Mercury Exposure on Oxidative Stress Profile

by Radu Ciprian Tincu, Cristian Cobilinschi, Iulia Alexandra Florea, Ana-Maria Cotae, Alexandru Emil Băetu, Sebastian Isac, Raluca Ungureanu, Gabriela Droc, Ioana Marina Grintescu and Liliana Mirea

Processes 2022, 10(11), 2388; https://doi.org/10.3390/pr10112388 - 14 Nov 2022

Cited by 2 | Viewed by 2683

Abstract

Background: The fish-based diet is known for its potential health benefits, but it is less known for its association with mercury (Hg) exposure, which, in turn, can lead to neurological and cardiovascular diseases through the exacerbation of oxidative stress. The aim of this [...] Read more.

Background: The fish-based diet is known for its potential health benefits, but it is less known for its association with mercury (Hg) exposure, which, in turn, can lead to neurological and cardiovascular diseases through the exacerbation of oxidative stress. The aim of this study was to evaluate the correlations between Hg blood concentration and specific biomarkers for oxidative stress. Methods: We present a cross-sectional, analytical, observational study, including primary quantitative data obtained from 67 patients who presented with unspecific complaints and had high levels of blood Hg. Oxidative stress markers, such as superoxide dismutase (SOD), glutathione peroxidase (GPX), malondialdehyde (MLD), lymphocyte glutathione (GSH-Ly), selenium (Se), and vitamin D were determined. Results: We found positive, strong correlations between Hg levels and SOD (r = 0.88, p < 0.0001), GPx (r = 0.92, p < 0.0001), and MLD (r = 0.94, p < 0.0001). We also found inverted correlations between GSH-Ly and vitamin D and Hg blood levels (r = −0.86, r = −0.91, respectively, both with p < 0.0001). Se had a weak correlation with Hg plasma levels, but this did not reach statistical significance (r = −0.2, p > 0.05). Conclusions: Thus, we can conclude that low-level Hg exposure can be an inductor of oxidative stress. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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13 pages, 2693 KiB

Open AccessArticle

The Electrochemical Reaction Kinetics during Synthetic Wastewater Treatment Using a Reactor with Boron-Doped Diamond Anode and Gas Diffusion Cathode

by Mohammad Issa, Dennis Haupt, Thorben Muddemann, Ulrich Kunz and Michael Sievers

Water 2022, 14(22), 3592; https://doi.org/10.3390/w14223592 - 8 Nov 2022

Cited by 1 | Viewed by 2348

Abstract

A system of boron-doped diamond (BDD) anode combined with a gas diffusion electrode (GDE) as a cathode is an attractive kind of electrolysis system to treat wastewater to remove organic pollutants. Depending on the operating parameters and water matrix, the kinetics of the [...] Read more.

A system of boron-doped diamond (BDD) anode combined with a gas diffusion electrode (GDE) as a cathode is an attractive kind of electrolysis system to treat wastewater to remove organic pollutants. Depending on the operating parameters and water matrix, the kinetics of the electrochemical reaction must be defined to calculate the reaction rate constant, which enables designing the treatment reactor in a continuous process. In this work, synthetic wastewater simulating the vacuum toilet sewage on trains was treated via a BDD-GDE reactor, where the kinetics was presented as the abatement of chemical oxygen demand (COD) over time. By investigating three different initial COD concentrations (C_0,1 ≈ 2 × C_0,2 ≈ 4 × C_0,3), the kinetics was presented and the observed reaction rate constant k_obs. was derived at different current densities (20, 50, 100 mA/cm²). Accordingly, a mathematical model has derived k_obs_. as a function of the cell potential

E_{c e l l}

. Ranging from 1 × 10⁻⁵ to 7.4 × 10⁻⁵ s⁻¹, the k_obs_. is readily calculated when

E_{c e l l}

varies in a range of 2.5–21 V. Furthermore, it was experimentally stated that the highest economic removal of COD was achieved at 20 mA/cm² demanding the lowest specific charge (~7 Ah/g_COD) and acquiring the highest current efficiency (up to ~48%). Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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12 pages, 3520 KiB

Open AccessArticle

Enhanced Catalytic Activity of a Coal-Based Powdered Activated Carbon by Thermal Treatment

by Do-Gun Kim, Tae-Hoon Kim and Seok-Oh Ko

Water 2022, 14(20), 3308; https://doi.org/10.3390/w14203308 - 19 Oct 2022

Cited by 5 | Viewed by 2122

Abstract

Thermal treatment is simple and has high potential in activated carbon (AC) modification because its functional groups, structures, and pores can be significantly modified. However, the changes in characteristics of ACs, affecting catalytic activity, have not been investigated enough. Therefore, in this study, [...] Read more.

Thermal treatment is simple and has high potential in activated carbon (AC) modification because its functional groups, structures, and pores can be significantly modified. However, the changes in characteristics of ACs, affecting catalytic activity, have not been investigated enough. Therefore, in this study, a coal-based powdered AC (PAC) was thermally treated, characterized, and subjected to the removal of an antibiotic (oxytetracycline, OTC). The PAC treated at 900 °C (PAC900) showed the best OTC removal compared to the PACs treated under lower temperatures via both adsorption and catalytic oxidation in the presence of peroxymonosulfate (PMS). The results of N₂ adsorption/desorption, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, and Boehm titration showed increases in basicity, specific surface area, graphitic structures with higher crystallinity and more defects, and C=O in PAC900 compared to PAC. Stronger signals of DMPO-X and TEMP-¹O₂ were shown for PAC900+PMS compared to PAC+PMS in electron paramagnetic resonance spectroscopy. It is suggested that a simple thermal treatment can significantly change the characteristics of a PAC, which improves organic micropollutants removal. The changes in the properties, affecting the performance, would provide important information about the improvement of carbonaceous catalysts. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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14 pages, 3477 KiB

Open AccessArticle

GO-TiO₂ as a Highly Performant Photocatalyst Maximized by Proper Parameters Selection

by Aida M. Díez, Marta Pazos, M. Ángeles Sanromán and Yury V. Kolen’ko

Int. J. Environ. Res. Public Health 2022, 19(19), 11874; https://doi.org/10.3390/ijerph191911874 - 20 Sep 2022

Cited by 8 | Viewed by 2189

Abstract

The synthesis and characterization of novel graphene oxide coupled to TiO₂ (GO-TiO₂) was carried out in order to better understand the performance of this photocatalyst, when compared to well-known TiO₂ (P25) from Degussa. Thus, its physical-chemical characterization (FTIR, XRD, [...] Read more.

The synthesis and characterization of novel graphene oxide coupled to TiO₂ (GO-TiO₂) was carried out in order to better understand the performance of this photocatalyst, when compared to well-known TiO₂ (P25) from Degussa. Thus, its physical-chemical characterization (FTIR, XRD, N₂ isotherms and electrochemical measurements) describes high porosity, suitable charge and high electron mobility, which enhance pollutant degradation. In addition, the importance of the reactor set up was highlighted, testing the effect of both the irradiated area and distance between lamp and bulb solution. Under optimal conditions, the model drug methylthioninium chloride (MC) was degraded and several parameters were assessed, such as the water matrix and the catalyst reutilization, a possibility given the addition of H₂O₂. The results in terms of energy consumption compete with those attained for the treatment of this model pollutant, opening a path for further research. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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9 pages, 3116 KiB

Open AccessArticle

Degradation of the UV Filter Benzophenone-4 by Ferrate (VI) in Aquatic Environments

by Rouyi Wang, Ping Sun, Zhicai Zhai, Hui Liu, Ruirui Han, Hongxia Liu and Yingsen Fang

Processes 2022, 10(9), 1829; https://doi.org/10.3390/pr10091829 - 10 Sep 2022

Cited by 2 | Viewed by 1727

Abstract

This work demonstrates the potential utility of ferrate(VI)-based advanced oxidation processes for the degradation of a representative UV filter, BP-4. The operational parameters of oxidant dose and temperature were determined with kinetic experiments. In addition, the effects of water constituents including anions (Cl [...] Read more.

This work demonstrates the potential utility of ferrate(VI)-based advanced oxidation processes for the degradation of a representative UV filter, BP-4. The operational parameters of oxidant dose and temperature were determined with kinetic experiments. In addition, the effects of water constituents including anions (Cl⁻, HCO₃⁻, NO₃⁻, SO₄²⁻), cations (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cu²⁺, Fe³⁺), and humic acid (HA) were investigated. Results suggested that the removal rate of BP-4 (5 mg/L) could reach 95% in 60 min, when [Fe(VI)]:[BP-4] = 100:1, T = 25 °C and pH = 7.0, The presence of K⁺, Cu²⁺ and Fe³⁺ could promote the removal of BP-4, but Cl⁻, SO₄²⁻, NO₃⁻, HA and Na⁺ could significantly inhibit the removal of BP-4. Furthermore, this Fe(VI) oxidation processes has good feasibility in real water samples. These results may provide useful information for the environmental elimination of benzophenone-type UV filters by Fe(VI). Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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16 pages, 5601 KiB

Open AccessArticle

White Light-Photolysis for the Removal of Polycyclic Aromatic Hydrocarbons from Proximity Firefighting Protective Clothing

by Aline Marcelino Arouca, Victor Emmanuel Delfino Aleixo, Maurício Leite Vieira, Márcio Talhavini and Ingrid Távora Weber

Int. J. Environ. Res. Public Health 2022, 19(16), 10054; https://doi.org/10.3390/ijerph191610054 - 15 Aug 2022

Cited by 3 | Viewed by 1829

Abstract

The presence of polycyclic aromatic hydrocarbons (PAHs) on firefighters’ personal protective equipment is a concern. One form of preventing from these compounds is to decontaminate proximity firefighting protective clothing (PFPC). Traditional decontamination methods do not promote total removal of pollutants and alter the [...] Read more.

The presence of polycyclic aromatic hydrocarbons (PAHs) on firefighters’ personal protective equipment is a concern. One form of preventing from these compounds is to decontaminate proximity firefighting protective clothing (PFPC). Traditional decontamination methods do not promote total removal of pollutants and alter the properties of PFPC. The objective of this work was to evaluate the effectiveness of white light-photolysis (WLP), an advanced oxidation process (AOP), for removing PAHs from PFPC, while maintaining the integrity of the fabric fibers. Experiments were carried out, varying reaction time and concentration of H₂O₂. With WLP (without H₂O₂), it was possible to remove more than 73% of the PAHs tested from the outer layer of PFPC in 3 days. The WLP provided the greatest removal of PAHs, compared with the most common mechanical decontamination techniques (laundering and wet-soap brushing). The fibers’ integrity after exposure to the white light was evaluated with infrared spectroscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. In addition, a tearing strength test was performed. No remarkable fabric degradation was observed, indicating a possible, routine-compatible, simple, and inexpensive method of decontamination of PFPC, based on photolysis, which is effective in the degradation of PAHs and maintains the integrity of fabric fibers. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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23 pages, 5636 KiB

Open AccessArticle

The Variations and Influences of the Channel Centerline of the Zhenjiang-Yangzhou Reach of the Yangtze River Based on Archival and Contemporary Data Sets

by Cunli Liu, Binglin Liu, Zhenke Zhang, Changfeng Li, Guoen Wei and Shengnan Jiang

Water 2022, 14(16), 2478; https://doi.org/10.3390/w14162478 - 11 Aug 2022

Cited by 1 | Viewed by 2344

Abstract

The Zhenjiang-Yangzhou reach of the Yangtze River is located at the top of the Yangtze River Delta, which is one of the most dramatic changes in the lower reaches of the Yangtze River. The study on the migration characteristics of the channel centerline [...] Read more.

The Zhenjiang-Yangzhou reach of the Yangtze River is located at the top of the Yangtze River Delta, which is one of the most dramatic changes in the lower reaches of the Yangtze River. The study on the migration characteristics of the channel centerline is crucial for a comprehensive understanding of the river channel changes in the Zhenjiang-Yangzhou reach. In this study, a detailed calculation method is proposed to extract the channel centerline of the Zhenjiang-Yangzhou reach by using old maps and remote sensing satellite map and decompose it into seven parts. The spatial and temporal changes of Net Shift Distance (NSD), Cumulative Moving Distance (CMD), Migration Rate of Channel Centerline (MRCC) and Linear Regression Change Rate of channel centerline (LRCR) from 1865 to 2019 on the cross-section scale are studied. The results show that: (1) from 1868 to 2019, the channel centerline of the Zhenjiang-Yangzhou reach kept shifting. The average net displacement distance of the section is 1103.47 m on the right bank, and the average cumulative displacement distance of the section is 2790.51 m. (2) According to the NSD and CMD data of each part, the long-term movement direction of the channel centerline is basically the same, and a small part of the channel centerline has periodic reverse swing. The probability of channel centerline moving right is about twice that of moving left. At the same time, some rivers have high erosion risk. (3) Through MRCC and LRCR data, the total number of channel centerline moving left and right is 156 and 329, respectively, and the erosion risk level of the near half of the shoreline is high. (4) The change of river boundary conditions and hydrodynamic force will affect the migration rate and direction of channel centerline. (5) This study proposes a method to extract channel centerline from a braided reach and study its changes, which can be applied to other similar reaches with a long history of human activities and high density. The results enrich people’s understanding of the long-term changes of a braided reach in the lower reaches of the Yangtze River and have certain guiding significance for river regulation, navigation safety, and revetment construction. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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18 pages, 2147 KiB

Open AccessArticle

Arsenite to Arsenate Oxidation and Water Disinfection via Solar Heterogeneous Photocatalysis: A Kinetic and Statistical Approach

by Felipe de J. Silerio-Vázquez, Cynthia M. Núñez-Núñez, José B. Proal-Nájera and María T. Alarcón-Herrera

Water 2022, 14(15), 2450; https://doi.org/10.3390/w14152450 - 8 Aug 2022

Cited by 2 | Viewed by 2346

Abstract

Arsenic (As) poses a threat to human health. In 2014, more than 200 million people faced arsenic exposure through drinking water, as estimated by the World Health Organization. Additionally, it is estimated that drinking water with proper microbiological quality is unavailable for more [...] Read more.

Arsenic (As) poses a threat to human health. In 2014, more than 200 million people faced arsenic exposure through drinking water, as estimated by the World Health Organization. Additionally, it is estimated that drinking water with proper microbiological quality is unavailable for more than 1 billion people. The present work analyzed a solar heterogeneous photocatalytic (HP) process for arsenite (As^III) oxidation and coliform disinfection from a real groundwater matrix employing two reactors, a flat plate reactor (FPR) and a compound parabolic collector (CPC), with and without added hydrogen peroxide (H₂O₂). The pseudo first-order reaction model fitted well to the As oxidation data. The treatments FPR–HP + H₂O₂ and CPC–HP + H₂O₂ yielded the best oxidation rates, which were over 90%. These treatments also exhibited the highest reaction rate constants, 6.7 × 10⁻³ min⁻¹ and 6.8 × 10⁻³ min⁻¹, respectively. The arsenic removal rates via chemical precipitation reached 98.6% and 98.7% for these treatments. Additionally, no coliforms were detected at the end of the process. The collector area per order (A_CO) for HP treatments was on average 75% more efficient than photooxidation (PO) treatments. The effects of the process independent variables, H₂O₂ addition, and light irradiation were statistically significant for the As^III oxidation reaction rate (p < 0.05). Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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24 pages, 8450 KiB

Open AccessArticle

Role of N-Doping and O-Groups in Unzipped N-Doped CNT Carbocatalyst for Peroxomonosulfate Activation: Quantitative Structure–Activity Relationship

by Kadarkarai Govindan, Do-Gun Kim and Seok-Oh Ko

Catalysts 2022, 12(8), 845; https://doi.org/10.3390/catal12080845 - 1 Aug 2022

Cited by 26 | Viewed by 2339

Abstract

We examined the relationship between the intrinsic structure of a carbocatalyst and catalytic activity of peroxomonosulfate (PMS) activation for acetaminophen degradation. A series of nitrogen-doped carbon nanotubes with different degrees of oxidation was synthesized by the unzipping method. The linear regression analysis proposes [...] Read more.

We examined the relationship between the intrinsic structure of a carbocatalyst and catalytic activity of peroxomonosulfate (PMS) activation for acetaminophen degradation. A series of nitrogen-doped carbon nanotubes with different degrees of oxidation was synthesized by the unzipping method. The linear regression analysis proposes that pyridinic N and graphitic N played a key role in the catalytic oxidation, rather than pyrrolic N and oxidized N. Pyridinic N reinforce the electron population in the graphitic framework and initiate the non-radical pathway via the formation of surface-bound radicals. Furthermore, graphitic N forms activated complexes (carbocatalyst-PMS*), facilitating the electron-transfer oxidative pathway. The correlation also affirms that -C=O was dominantly involved as a main active site, rather than -C-OH and -COOH. This study can be viewed as the first attempt to demonstrate the relationship between the fraction of N-groups and activity, and the quantity of O-groups and activity by active species (quenching studies) was established to reveal the role of N-groups and O-groups in the radical and non-radical pathways. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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13 pages, 1769 KiB

Open AccessArticle

Degradation of Diazepam with Gamma Radiation, High Frequency Ultrasound and UV Radiation Intensified with H₂O₂ and Fenton Reagent

by Michel Manduca Artiles, Susana Gómez González, María A. González Marín, Sarra Gaspard and Ulises J. Jauregui Haza

Processes 2022, 10(7), 1263; https://doi.org/10.3390/pr10071263 - 27 Jun 2022

Cited by 1 | Viewed by 2580

Abstract

A degradation study of diazepam (DZP) in aqueous media by gamma radiation, high frequency ultrasound, and UV radiation (artificial-solar), as well with each process intensified with oxidizing agents (H₂O₂ and Fenton reagent) was performed. The parameters that influence the degradation [...] Read more.

A degradation study of diazepam (DZP) in aqueous media by gamma radiation, high frequency ultrasound, and UV radiation (artificial-solar), as well with each process intensified with oxidizing agents (H₂O₂ and Fenton reagent) was performed. The parameters that influence the degradation of diazepam such as potency and frequency, irradiation dose, pH and concentration of the oxidizing agents used were studied. Gamma radiation was performed in a ⁶⁰Co source irradiator; an 11 W lamp was used for artificial UV radiation, and sonification was performed at frequency values of 580 and 862 kHz with varying power values. In the radiolysis a 100% degradation was obtained at 2500 Gy. For the sonolysis, 28.3% degradation was achieved after 180 min at 862 kHz frequency and 30 W power. In artificial photolysis, a 38.2% degradation was obtained after 300 min of UV exposure. The intensification of each process with H₂O₂ increased the degradation of the drug. However, the best results were obtained by combining the processes with the Fenton reagent for optimum H₂O₂ and Fe²⁺ concentrations, respectively, of 2.95 mmol L⁻¹ and of 0.06 mmol L⁻¹, achieving a 100% degradation in a shorter treatment time, with a dose value of 750 Gy in the case of gamma radiation thanks to increasing in the amount of free radicals in water. The optimized processes were evaluated in a real wastewater, with a total degradation at 10 min of reaction. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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9 pages, 1854 KiB

Open AccessArticle

Methodology for Simultaneous Analysis of Photocatalytic deNO_x Products

by Jan Suchanek, Eva Vaneckova, Michal Dostal, Eliska Mikyskova, Libor Brabec, Radek Zouzelka and Jiri Rathousky

Catalysts 2022, 12(6), 661; https://doi.org/10.3390/catal12060661 - 16 Jun 2022

Cited by 2 | Viewed by 1889

Abstract

The ISO standard 22197-1:2016 used for the evaluation of the photocatalytic nitric oxide removal has a main drawback, which allows only the decrease of nitric oxide to be determined specifically. The remaining amount, expressed as “NO₂”, is considered as a sum [...] Read more.

The ISO standard 22197-1:2016 used for the evaluation of the photocatalytic nitric oxide removal has a main drawback, which allows only the decrease of nitric oxide to be determined specifically. The remaining amount, expressed as “NO₂”, is considered as a sum of HNO₃, HONO NO₂, and other nitrogen-containing species, which can be potentially formed during the photocatalytic reaction. Therefore, we developed a new methodology combining our custom-made analyzers, which can accurately determine the true NO₂ and HONO species, with the conventional NO one. Their function was validated via a photocatalytic experiment in which 100 ppbv of either NO or NO₂ dispersed in air passed over (3 L min⁻¹) an Aeroxide© TiO₂ P25 surface. The gas-phase analysis was complemented with the spectrophotometric determination of nitrates

({NO}_{3}^{-})

and/or nitrites (

{NO}_{2}^{-})

deposited on the P25 layer. Importantly, an almost perfect mass balance (94%) of the photocatalytic NOx abatement was achieved. The use of custom-made analyzers enables to obtain (i) no interference, (ii) high sensitivity, (iii) good linearity in the relevant concentration range, (iv) rapid response, and (v) long-term stability. Therefore, our approach enables to reveal the reaction complexity and is highly recommended for the photocatalytic NOx testing. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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15 pages, 4299 KiB

Open AccessArticle

Vital Role of Synthesis Temperature in Co–Cu Layered Hydroxides and Their Fenton-like Activity for RhB Degradation

by Ruixue Zhang, Yanping Liu, Xinke Jiang and Bo Meng

Catalysts 2022, 12(6), 646; https://doi.org/10.3390/catal12060646 - 13 Jun 2022

Cited by 4 | Viewed by 2128

Abstract

Cu and Co have shown superior catalytic performance to other transitional elements, and layered double hydroxides (LDHs) have presented advantages over other heterogeneous Fenton catalysts. However, there have been few studies about Co–Cu LDHs as catalysts for organic degradation via the Fenton reaction. [...] Read more.

Cu and Co have shown superior catalytic performance to other transitional elements, and layered double hydroxides (LDHs) have presented advantages over other heterogeneous Fenton catalysts. However, there have been few studies about Co–Cu LDHs as catalysts for organic degradation via the Fenton reaction. Here, we prepared a series of Co–Cu LDH catalysts by a co-precipitation method under different synthesis temperatures and set Rhodamine B (RhB) as the target compound. The structure-performance relationship and the influence of reaction parameters were explored. A study of the Fenton-like reaction was conducted over Co–Cu layered hydroxide catalysts, and the variation of synthesis temperature greatly influenced their Fenton-like catalytic performance. The Co–Cu_t=65°C catalyst with the strongest LDH structure showed the highest RhB removal efficiency (99.3% within 30 min). The change of synthesis temperature induced bulk-phase transformation, structural distortion, and metal–oxygen (M–O) modification. An appropriate temperature improved LDH formation with defect sites and lengthened M–O bonds. Co–Cu LDH catalysts with a higher concentration of defect sites promoted surface hydroxide formation for H₂O₂ adsorption. These oxygen vacancies (Ovs) promoted electron transfer and H₂O₂ dissociation. Thus, the Co–Cu LDH catalyst is an attractive alternative organic pollutants treatment. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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18 pages, 5771 KiB

Open AccessArticle

Unusual Catalytic Effect of Fe³⁺ on 2,4-dichlorophenoxyacetic Acid Degradation by Radio Frequency Discharge in Aqueous Solution

by Yongjun Liu and Bing Sun

Water 2022, 14(11), 1719; https://doi.org/10.3390/w14111719 - 27 May 2022

Cited by 4 | Viewed by 2245

Abstract

2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide for controlling broad-leaved weeds. The development of an efficient process for treating the refractory 2,4-D wastewater is necessary. In this study, liquid-phase degradation of 2,4-D induced by radio frequency discharge (RFD) was studied. Experimental results [...] Read more.

2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide for controlling broad-leaved weeds. The development of an efficient process for treating the refractory 2,4-D wastewater is necessary. In this study, liquid-phase degradation of 2,4-D induced by radio frequency discharge (RFD) was studied. Experimental results showed that the degradation was more effective in acidic than in neutral or alkaline solutions. During the degradation, a large amount of hydrogen peroxide (H₂O_2, 1.2 mM/min, almost equal to that without 2,4-D) was simultaneously produced, and catalytic effects of both ferric (Fe³⁺) and ferrous (Fe²⁺) ions on the degradation were examined and compared. It was found that 2,4-D degraded more rapidly in the case of Fe³⁺ than the that of Fe²⁺. Such a scenario is explained that Fe³⁺ was successively reduced to Fe²⁺ by the atomic hydrogen (•H) and •OH-adducts of 2,4-D resulting from RFD, which in turn catalyzed the H₂O₂ to form more •OH radicals through Fenton’s reaction, indicating that Fe³⁺ not only accelerates the degradation rate but also increases the amount of •OH available for 2,4-D degradation by suppressing the back reaction between the •H and •OH. 2,4-dichlorophenol, 4,6-dichlororesorcinol, 2-hydroxy-4-chloro- and 2-chloro-4-hydroxy- phenoxyacetic acids, hydroxylated 2,4-Ds, and carboxylic acids (glycolic, formic and oxalic) were identified as the byproducts. Energy yields of RFD have been compared with those of other nonthermal plasma processes. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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14 pages, 3728 KiB

Open AccessArticle

Heat/PMS Degradation of Atrazine: Theory and Kinetic Studies

by Yixin Lu, Yujie Liu, Chenghan Tang, Jiao Chen and Guo Liu

Processes 2022, 10(5), 941; https://doi.org/10.3390/pr10050941 - 9 May 2022

Cited by 13 | Viewed by 2326

Abstract

The degradation effect of heat/peroxymonosulfate (PMS) on atrazine (ATZ) is studied. The results show that the heat/PMS degradation for ATZ is 96.28% at the moment that the phosphate buffer (PB) pH, temperature, PMS dosage, ATZ concentration, and reaction time are 7, 50 °C, [...] Read more.

The degradation effect of heat/peroxymonosulfate (PMS) on atrazine (ATZ) is studied. The results show that the heat/PMS degradation for ATZ is 96.28% at the moment that the phosphate buffer (PB) pH, temperature, PMS dosage, ATZ concentration, and reaction time are 7, 50 °C, 400 μmol/L, 2.5 μmol/L, and 60 min. A more alkaline PB is more likely to promote the breakdown of ATZ through heat/PMS, while the PB alone has a more acidic effect on the PMS than the partially alkaline solution.

HO •

and

S O_{4}^{-} •

coexisted within the heat/PMS scheme, and ATZ quantity degraded by

HO •

and

S O_{4}^{-} •

in PB with pH = 7, pH = 1.7~1.

HC O_{3}^{-}

makes it difficult for heat/PMS to degrade ATZ according to inorganic anion studies, while

C l^{-}

and

N O_{3}^{-}

accelerate the degradation and the acceleration effect of

N O_{3}^{-}

is more obvious. The kinetics of ATZ degradation via heat/PMS is quasi-first-order. Ethanol (ETA) with the identical concentration inhibited ATZ degradation slightly more than

HC O_{3}^{-}

, and both of them reduced the degradation rates of heat/PMS to 7.06% and 11.56%. The addition of

C l^{-}

and

N O_{3}^{-}

increased the maximum rate of ATZ degradation by heat/PMS by 62.94% and 189.31%. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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12 pages, 2767 KiB

Open AccessArticle

Changes in Organics and Nitrogen during Ozonation of Anaerobic Digester Effluent

by Jesmin Akter, Jaiyeop Lee, Weonjae Kim and Ilho Kim

Water 2022, 14(9), 1425; https://doi.org/10.3390/w14091425 - 29 Apr 2022

Cited by 6 | Viewed by 2753

Abstract

The objective of this study is to investigate the consequence of ozone dosage rate on the qualitative change in organic compounds and nitrogen in anaerobic digester effluent during the ozone process. Therefore, ozonation improves the biodegradability of recalcitrant organic compounds, quickly oxidizes the [...] Read more.

The objective of this study is to investigate the consequence of ozone dosage rate on the qualitative change in organic compounds and nitrogen in anaerobic digester effluent during the ozone process. Therefore, ozonation improves the biodegradability of recalcitrant organic compounds, quickly oxidizes the unsaturated bond, and forms radicals that continue to deteriorate other organic matter. In this study, ozonation was performed in a microbubble column reactor; the use of microbubble ozone improves the status of chemical oxygen demand (COD) and changes of organic nitrogen to inorganic compounds. The ozone injection rates were 1.0, 3.2, and 6.2 mg/L/min. The samples obtained during the ozone treatments were monitored for COD_Mn, COD_Cr, TOC, NO₂⁻-N, NO₃⁻-N, NH₄⁺-N, T-N, and Org-N. The ozone dose increased 1.0 to 6.2 mg/L and it increased the degradation ratio 40% and the total organic carbon 20% during 20 min of reaction time. During the ozonation, the COD_Cr and COD_Mn values were increased per unit of ozone consumption. The ozone treatment showed organic nitrogen mineralization and degradation of organic compounds with the contribution of the microbubble ozone oxidation process and is a good option for removing non-biodegradable organic compounds. The original application of the microbubble ozone process, with the degradation of organic compounds from a domestic wastewater treatment plant, was investigated. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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12 pages, 2318 KiB

Open AccessFeature PaperArticle

Mechanistic Insight into Degradation of Cetirizine under UV/Chlorine Treatment: Experimental and Quantum Chemical Studies

by Boyi Zhu, Fangyuan Cheng, Wenjing Zhong, Jiao Qu, Ya-nan Zhang and Hongbin Yu

Water 2022, 14(9), 1323; https://doi.org/10.3390/w14091323 - 19 Apr 2022

Cited by 4 | Viewed by 2483

Abstract

UV/chlorine treatment is an efficient technology for removing organic pollutants in wastewater. Nevertheless, degradation of antihistamines in the UV/chlorine system, especially the underlying reaction mechanism, is not yet clear. In this study, the degradation of cetirizine (CTZ), a representative antihistamine, under UV/chlorine treatment [...] Read more.

UV/chlorine treatment is an efficient technology for removing organic pollutants in wastewater. Nevertheless, degradation of antihistamines in the UV/chlorine system, especially the underlying reaction mechanism, is not yet clear. In this study, the degradation of cetirizine (CTZ), a representative antihistamine, under UV/chlorine treatment was investigated. The results showed that CTZ could undergo fast degradation in the UV/chlorine system with an observed reaction rate constant (k_obs) of (0.19 ± 0.01) min⁻¹, which showed a first-increase and then-decrease trend with its initial concentration increased. The degradation of CTZ during the UV/chlorine treatment was attributed to direct UV irradiation (38.7%), HO^• (35.3%), Cl^• (7.3%), and ClO^• (17.1%). The k_obs of CTZ decreased with the increase in pH and the increase in concentrations of a representative dissolved organic matter, Suwannee River natural organic matter (SRNOM), due to their negative effects on the concentrations of reactive species generated in the UV/chlorine system. The detailed reaction pathways of HO^•, ClO^•, and Cl^• with CTZ were revealed using quantum chemical calculation. This study provided significant insights into the efficient degradation and the underlying mechanism for the removal of CTZ in the UV/chlorine system. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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26 pages, 1444 KiB

Open AccessReview

The Influence of Synthesis Methods and Experimental Conditions on the Photocatalytic Properties of SnO₂: A Review

by Jéssica Luisa Alves do Nascimento, Lais Chantelle, Iêda Maria Garcia dos Santos, André Luiz Menezes de Oliveira and Mary Cristina Ferreira Alves

Catalysts 2022, 12(4), 428; https://doi.org/10.3390/catal12040428 - 11 Apr 2022

Cited by 27 | Viewed by 4003

Abstract

Semiconductors based on transition metal oxides represent an important class of materials used in emerging technologies. For this, the performance of these materials strongly depends on the size and morphology of particles, surface charge characteristics, and the presence of bulk and surface defects [...] Read more.

Semiconductors based on transition metal oxides represent an important class of materials used in emerging technologies. For this, the performance of these materials strongly depends on the size and morphology of particles, surface charge characteristics, and the presence of bulk and surface defects that are influenced by the synthesis method and the experimental conditions the materials are prepared. In this context, the present review aims to report the importance of choosing the synthesis methods and experimental conditions to modify structural, morphological, and electronic characteristics of semiconductors, more specifically, tin oxide (SnO₂), since these parameters may be a determinant for better performance in various applications, including photocatalysis. SnO₂ is an n-type semiconductor with a band gap between 3.6 and 4.0 eV, whose intrinsic characteristics are responsible for its electrical conductivity, good optical characteristics, high thermal stability, and other qualities. Such characteristics have provided excellent results in advanced oxidative processes, i.e., heterogeneous photocatalysis applications. This process involves semiconductors in the production of hydroxyl radicals via activation by light absorption, and it is considered as an emerging and promising technology for domestic-industrial wastewater treatment. In our review article, we focused on the photodegradation of different organic dyes and types of persistent organic pollutants using SnO₂-based photocatalysts, and how the efficiency of these materials can be impacted by synthesis methods and experimental conditions employed to prepare them. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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